Complete machine performance calculation method of pulse detonation turbofan engine

Abstract

The invention relates to a complete machine performance calculation method of a pulse detonation turbofan engine, which comprises the following steps of: performing design point performance calculation according to an air inlet channel, a fan component, an air compressor component, a mixing chamber and an exhaust nozzle of the pulse detonation turbofan engine; according to the method, performance calculation is sequentially carried out on a gas compressor component, a pulse detonation combustion chamber and a turbine component in the inner duct and the outer duct, obtained outlet parameters of the inner duct and the outer duct are compared with an iterative fan pressure ratio for judgment till static pressure balance of the inner duct and the outer duct is achieved, and finally performance parameters of the engine are obtained. The engine thrust is FN, the engine unit thrust is FS, and the engine unit oil consumption rate is SFC. When the method is used for overall design of the aero-engine, the pressure ratio of compression parts of the pulse detonation turbine engine can be effectively reduced, then the number of stages of a gas compressor and a turbine is reduced, the mass of the engine is reduced, the thrust-mass ratio of the engine is increased, finally, the performance of the engine is improved, and the iteration period of the overall design of the pulse detonation turbine engine is effectively shortened.

Description

Technical Field

[0001] The invention relates to the field of aviation turbine engines, and in particular to a method for calculating the overall performance of a turbofan engine taking into account a pulse detonation combustion chamber. Background Art

[0002] As the epitome of high-end equipment manufacturing, aviation turbine engines are known as the jewel in the crown of industry because of their extremely demanding and complex design and manufacturing requirements. Their technology is the highest embodiment of a country's scientific and technological level and comprehensive technical capabilities, and can be used to measure a country's comprehensive national strength. The overall design of aviation engines is the top-level design of R&D technology and the soul of aviation engines.

[0003] The pulse detonation engine (PDE) uses periodic detonation waves to generate high-temperature and high-pressure combustion gas to generate thrust. It has the advantages of high cycle thermal efficiency and simple structure.

[0004] Based on the turbofan engine, a pulse detonation combustor (PDC) is used to replace the isobaric combustion chamber in the traditional turbojet engine to form a turbofan-pulse detonation combination engine, namely a pulse detonation turbofan engine. This engine changes from an isobaric cycle to a detonation cycle (approximately a isochoric cycle) and thus improves the thermal efficiency of the cycle.

[0005] The overall performance parameters are the key to the overall design and determine the advanced level of the engine. The accurate design of the overall performance of the pulse detonation turbofan engine can help the overall designers quickly determine whether its performance parameters meet the requirements, shorten the iteration cycle of the overall design, and improve the design efficiency. Therefore, it is urgent to provide a method that can calculate the overall performance of the pulse detonation turbofan engine. Summary of the invention

[0006] The purpose of the present invention is to avoid the shortcomings of the prior art and provide a method that can quickly and accurately estimate the average parameters of the pulse detonation combustion chamber outlet and construct a high-precision whole-machine component-level variable specific thermal performance calculation model.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for calculating the overall performance of a pulse detonation turbofan engine, comprising the following steps:

[0008] Step 1: using a variable specific heat calculation method, the design point performance calculations are performed on the air inlet, fan components, compressor components, mixing chamber and tail nozzle of the pulse detonation turbofan engine in turn, and the inner and outer bypass of the pulse detonation turbofan engine are determined according to the engine bypass ratio BPR and the fan pressure ratio PRF in the design point;

[0009] Step 2, calculate the outlet total temperature T3 and outlet total pressure P3 of the compressor components in the inner channel, and then according to the compressor outlet total temperature T3 and outlet total pressure P3 and the detonation tube number NUMB, tube length L, tube diameter D, operating frequency f and detonation combustion chamber outlet total temperature T4 of the detonation combustion chamber, and take the total temperature and total pressure of the pressure platform area at the thrust wall of the detonation chamber as the equivalent total temperature and total pressure at the outlet of the detonation chamber, according to the detonation wave structure model, the average parameters of the pulse detonation combustion chamber outlet are obtained;

[0010] Step 3: According to the total temperature T4, total pressure P4 and high-pressure turbine efficiency ET of the detonation combustion chamber outlet HP , low pressure turbine efficiency ET LP , the total temperature T5 and total pressure P5 of the turbine outlet are obtained by iterative calculation, which are the internal channel outlet parameters of the pulse detonation engine;

[0011] Step 4: Based on the known total pressure loss DP in the outer duct DU , Mach number Ma, judge whether the static pressure of inner and outer culvert is balanced. If it is close, perform the design point performance calculation of mixing chamber and tail nozzle. Otherwise, continue to iterate and calculate the fan pressure ratio PRF until the static pressure of inner and outer culvert is balanced. At this time, the static pressure residual of inner and outer culvert is ≤e -4 ;

[0012] Finally, the engine performance parameters are obtained, including engine thrust FN, engine unit thrust FS, and engine unit fuel consumption SFC.

[0013] Furthermore, the specific process of calculating the outlet total temperature T3 and outlet total pressure P3 of the compressor components in the inner channel in step 2 is:

[0014] Step 21: Under the conditions of a given flight Mach number Ma and a flight altitude H of zero, according to the atmospheric temperature T of the standard atmosphere at sea level s0 With atmospheric pressure P s0 The total temperature T1 and total pressure P1 of the air in the intake duct are calculated by the calculation formula of total parameters and static parameters;

[0015] Step 22: Calculate the outlet total temperature T of the fan component by using the fan / compressor pressure ratio calculation formula according to the engine bypass ratio BPR, the fan pressure ratio PRF of the fan component, the fan efficiency ETAF, the compressor pressure ratio CPR, the compressor efficiency ETAC, and the air flow Wa. 21 and outlet total pressure P 21 And the compressor outlet total temperature T3 and outlet total pressure P3.

[0016] Furthermore, the specific calculation process of the average parameters of the pulse detonation combustion chamber outlet in step 2 is:

[0017] According to the detonation wave structure model, the calculation formula for the total pressure and total temperature at the thrust wall of the detonation chamber is:

[0018]

[0019] T H =T CJ [1-(γ2-1) / 2Ma CJ ] 2 ,

[0020] Where: P H is the pressure at the thrust wall; P CJ is the pressure at the CJ point of the detonation wave; T H is the temperature at the thrust wall; T CJ is the temperature of the detonation wave CJ point, γ is the specific heat ratio; Ma CJ is the detonation wave Mach number;

[0021] The filling Mach number Ma given by the design point fill The static pressure and static temperature inside the pulse detonation combustion chamber after the filling stage is completed are obtained by using the static temperature and static pressure stagnation parameters. The specific heat capacity and enthalpy of the working fluid are calculated by REFPROP, and the detonation wave Mach number Ma CJ , speed V CJ The parameters were calculated using NASA's chemical balance application software.

[0022] The working fluid in the pulse detonation combustion chamber flows radially and uniformly, the flow rates at the inlet and outlet of the pulse detonation combustion chamber are equal in the same detonation cycle, the pressure platform, pressure decay and filling stages of the pulse detonation combustion chamber are all isentropic thermodynamic processes, the back propagation of the detonation wave of the pulse detonation combustion chamber is ignored, and under ideal conditions with only 20-25% pressure loss and no time lag between the filling stage of the pulse detonation combustion chamber and the formation of the detonation wave at the closed end, the average parameters of the outlet of the pulse detonation combustion chamber are calculated using NASA's chemical balance application software, and the average parameters of the outlet include the flow rate W of the outlet of the pulse detonation combustion chamber. g4 , outlet total temperature T4, outlet total pressure P t , the outlet oil-gas ratio FAR4, as the equivalent total parameter of the detonation combustion chamber outlet, is used to calculate the performance of the pulse detonation turbine engine.

[0023] Furthermore, the outlet total temperature T4, outlet total pressure P t The specific calculation process is:

[0024] First, the total pressure in the pressure plateau area is:

[0025] p plateau =δ A1 p s,fill ,

[0026]

[0027] Where p s，fill is the static pressure in the pulse detonation combustion chamber after filling is completed, δ A1 It is a gas characteristic parameter, which characterizes the pressure increase ratio of the total pressure in the pressure platform area relative to the static pressure in the filling stage. k1 and k2 are the specific heat ratio of the fuel-air mixture before detonation and the specific heat ratio of the products after detonation, respectively.

[0028] Under isentropic conditions, according to the relationship between sound velocity and temperature, the total temperature of the pressure platform area after the detonation wave is initiating, the sound velocity c after the detonation is obtained. b Calculated by the following formula, δ A2 It is a characteristic parameter to characterize the pressure decay.

[0029] c b =V CJ / δ A2 ,

[0030]

[0031] The propagation time of the blast wave is t CJ It is obtained from the following formula, L is the length of the pulse detonation combustion chamber, V fill is the filling velocity of the pulse detonation combustion chamber at the initial moment.

[0032]

[0033] Duration of pressure plateau area t plateau Calculated by the following formula, where δ B is the gas characteristic parameter, which characterizes its propagation time t with the detonation wave CJ Ratio of:

[0034] t plateau =δ B t CJ ,

[0035]

[0036] Duration of the pressure decay phase t decay Calculated by the following formula, where function f n (δ A2 ) According to the thrust wall pressure decay function table with time:

[0037] t decay =t CJ δ A2 [f n (δ A2 )-1];

[0038] Finally, the calculation formula for filling time is:

[0039]

[0040] In summary, the total parameters and corresponding time of the filling stage, pressure platform stage and pressure decay stage are calculated by the above formulas. The calculation formula for the working time of the detonation chamber is:

[0041] t cycle =t CJ +t plateau +t decay ,

[0042] The average total temperature and total pressure at the outlet of the pulse detonation combustion chamber can also be calculated:

[0043]

[0044] in:

[0045]

[0046] Where u(t) is the air flow velocity at time t, D tube is the pipe diameter, N tube is the number of tubes, f is the operating frequency, P tout That is equivalent to the total pressure P4 at the outlet of the detonation chamber, T tout That is equivalent to the total temperature T4 at the detonation chamber outlet.

[0047] Furthermore, the specific calculation process of the total pressure P5 in step 3 is:

[0048] The residual equation of the whole machine performance model is established:

[0049] ERR=(P 5I -P 5O ) / P 5I

[0050] P5=f(FanPR),

[0051] Where P 5I is the total pressure at the outlet of the low-pressure turbine, P 5O is the total pressure at the outer duct outlet, and the independent variable is the fan pressure ratio; that is, by changing the fan pressure ratio, the total pressure of the two sections is adjusted to make them basically consistent, reducing the mixing loss and ensuring the stable operation of the mixing chamber.

[0052] Furthermore, the design point of the mixing chamber in step 4 is obtained by the static pressure balance equation of the inner and outer ducts at the mixing chamber inlet, the total temperature T6 of the mixing chamber outlet, the total pressure P6 of the mixing chamber outlet, the total temperature and pressure of the tail nozzle inlet, and the velocity coefficient C V After isentropic calculation, the tail nozzle outlet area A9 and air flow velocity V9 are obtained.

[0053] The beneficial effect of the present invention is that when performing performance calculations, the present invention replaces the isobaric combustion chamber in a traditional turbojet engine with a pulse detonation combustion chamber, so that the engine is converted from an isobaric cycle to a detonation cycle (approximately an isochoric cycle) to improve the thermal efficiency of the cycle. That is, after calculating the average parameters of the pulse detonation combustion chamber outlet, the pulse detonation combustion chamber is taken as a conventional engine component and brought into the overall performance model to obtain more accurate performance results.

[0054] The pulse detonation combustion chamber has the characteristic of self-pressurization. When conducting the overall design of an aero-engine, it can effectively reduce the compression ratio of the compression components of the pulse detonation turbine engine, thereby reducing the number of compressor and turbine stages, thereby reducing the engine mass, further improving the engine thrust-to-mass ratio, and ultimately improving the engine performance, effectively shortening the iteration cycle of the overall design of the pulse detonation turbine engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is the flow chart of the whole machine performance calculation. DETAILED DESCRIPTION

[0056] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0057] In order to achieve the above object, the present invention provides the following specific implementation methods:

[0058] Embodiment 1: A method for calculating the overall performance of a pulse detonation turbofan engine, comprising the following steps:

[0059] Step 1: Using the variable specific heat calculation method, the design point performance calculations are performed on the inlet, fan components, compressor components, mixing chamber and tail nozzle of the pulse detonation turbofan engine in turn, and the inner and outer bypass of the pulse detonation turbofan engine are determined according to the engine bypass ratio BPR and fan pressure ratio PRF in the design point;

[0060] Step 2, calculate the outlet total temperature T3 and outlet total pressure P3 of the compressor components in the inner channel, and then according to the compressor outlet total temperature T3 and outlet total pressure P3 and the detonation tube number NUMB, tube length L, tube diameter D, operating frequency f and detonation combustion chamber outlet total temperature T4 of the detonation combustion chamber, and take the total temperature and total pressure of the pressure platform area at the thrust wall of the detonation chamber as the equivalent total temperature and total pressure at the outlet of the detonation chamber, according to the detonation wave structure model, the average parameters of the pulse detonation combustion chamber outlet are obtained;

[0061] The specific process of calculating the outlet total temperature T3 and outlet total pressure P3 of the compressor components in the inner channel is:

[0062] Step 21: Under the conditions of a given flight Mach number Ma and a flight altitude H of zero, according to the atmospheric temperature T of the standard atmosphere at sea level s0 With atmospheric pressure P s0 The total temperature T1 and total pressure P1 of the air in the intake duct are calculated by the calculation formula of total parameters and static parameters;

[0063] Step 22: Calculate the outlet total temperature T of the fan component by using the fan / compressor pressure ratio calculation formula according to the engine bypass ratio BPR, the fan pressure ratio PRF of the fan component, the fan efficiency ETAF, the compressor pressure ratio CPR, the compressor efficiency ETAC, and the air flow Wa. 21 and outlet total pressure P 21 And the compressor outlet total temperature T3 and outlet total pressure P3.

[0064] The specific calculation process of the average parameters of the pulse detonation combustion chamber outlet is as follows:

[0065] According to the detonation wave structure model, the calculation formula for the total pressure and total temperature at the thrust wall of the detonation chamber is:

[0066]

[0067] T H =T CJ [1-(γ2-1) / 2Ma CJ ] 2 ,

[0068] Where: P H is the pressure at the thrust wall; P CJ is the pressure at the CJ point of the detonation wave; T H is the temperature at the thrust wall; T CJ is the temperature of the detonation wave CJ point, γ is the specific heat ratio; Ma CJ Mach number of the detonation wave CJ point;

[0069] The working fluid in the pulse detonation combustion chamber flows radially uniformly, the flow rates at the inlet and outlet of the pulse detonation combustion chamber are equal in the same detonation cycle, the pressure platform, pressure decay and filling stages of the pulse detonation combustion chamber are all isentropic thermodynamic processes, the back propagation of the detonation wave of the pulse detonation combustion chamber is ignored, and there is only 20-25% pressure loss and no time lag between the filling stage of the pulse detonation combustion chamber and the formation of the detonation wave at the closed end. Under ideal conditions, the average parameters of the pulse detonation combustion chamber outlet are calculated using NASA's chemical balance application software, and the average parameters of the outlet include the flow rate W of the pulse detonation combustion chamber outlet. g4 , outlet total temperature T4, outlet total pressure P t , the outlet oil-gas ratio FAR4, as the equivalent total parameter of the detonation combustion chamber outlet, is used to calculate the performance of the pulse detonation turbine engine.

[0070] Furthermore, the outlet total temperature T4 and outlet total pressure P t The specific calculation process is:

[0071] First, the total pressure in the pressure plateau area is:

[0072] p plateau =δ A1 p s,fill ,

[0073]

[0074] Where p s，fill is the static pressure in the pulse detonation combustion chamber after filling is completed, δ A1 It is a gas characteristic parameter, which characterizes the pressure increase ratio of the total pressure in the pressure platform area relative to the static pressure in the filling stage. k1 and k2 are the specific heat ratio of the fuel-air mixture before detonation and the specific heat ratio of the products after detonation, respectively.

[0075] Under isentropic conditions, according to the relationship between sound velocity and temperature, the total temperature of the pressure platform area after the detonation wave is initiating, the sound velocity c after the detonation is obtained. b Calculated by the following formula, δ A2 It is the characteristic parameter to characterize the pressure decay;

[0076] c b =V CJ / δ A2 ,

[0077]

[0078] The propagation time of the blast wave is t CJ It is obtained from the following formula, L is the length of the pulse detonation combustion chamber, V fill is the filling velocity of the pulse detonation combustion chamber at the initial moment;

[0079]

[0080] Duration of pressure plateau area t plateau Calculated by the following formula, where δ B is the gas characteristic parameter, which characterizes its propagation time t with the detonation wave CJ Ratio of:

[0081] t plateau =δ B t CJ ,

[0082]

[0083] Duration of the pressure decay phase t decay Calculated by the following formula, where function f n (δA2 ) According to the thrust wall pressure decay function table with time, as shown in Table 1:

[0084] t decay =t CJ δ A2 [f n (δ A2 )-1];

[0085] Table 1 Thrust wall pressure decay function with time

[0086]

[0087] Finally, the calculation formula for filling time is:

[0088]

[0089] In summary, the total parameters and corresponding time of the filling stage, pressure platform stage and pressure decay stage are calculated by the above formulas. The calculation formula for the working time of the detonation chamber is:

[0090] t cycle =t CJ +t plateau +t decay ,

[0091] The average total temperature and total pressure at the outlet of the pulse detonation combustion chamber can also be calculated:

[0092]

[0093] in:

[0094]

[0095] Where u(t) is the air flow velocity at time t, D tube is the pipe diameter, N tube is the number of tubes, f is the operating frequency, P tout That is equivalent to the total pressure P4 at the outlet of the detonation chamber, T tout That is equivalent to the total temperature T4 at the detonation chamber outlet.

[0096] Step 3: According to the total temperature T4, total pressure P4 and high-pressure turbine efficiency ET of the detonation combustion chamber outlet HP , low pressure turbine efficiency ET LP , the total temperature T5 and total pressure P5 of the turbine outlet are obtained through iterative calculation, which are the internal channel outlet parameters of the pulse detonation engine;

[0097] Among them, the specific calculation process of the total pressure P5 is:

[0098] The residual equation of the whole machine performance model is established:

[0099] ERR=(P 5I -P 5O ) / P 5I

[0100] P5=f(FanPR),

[0101] Where P 5I is the total pressure at the outlet of the low-pressure turbine, P 5O is the total pressure at the outer duct outlet, and the independent variable is the fan pressure ratio; that is, by changing the fan pressure ratio, the total pressure of the two sections is adjusted to make them basically consistent, reducing the mixing loss and ensuring the stable operation of the mixing chamber.

[0102] Step 4: Based on the known total pressure loss DP in the outer duct DU , Mach number Ma, judge whether the static pressure of inner and outer culvert is balanced. If it is close, perform the design point performance calculation of mixing chamber and tail nozzle. Otherwise, continue to iteratively calculate the fan pressure ratio PRF until the static pressure of inner and outer culvert is balanced. At this time, the static pressure residual of inner and outer culvert is ≤e -4 ;

[0103] Among them, the design point of the mixing chamber is the static pressure balance equation of the inner and outer ducts at the mixing chamber inlet, and the total temperature T6 and total pressure P6 of the mixing chamber outlet are obtained. The total temperature and total pressure of the tail nozzle inlet are known, and the velocity coefficient C V After isentropic calculation, the tail nozzle outlet area A9 and air flow velocity V9 are obtained.

[0104] Finally, the engine performance parameters are obtained, including engine thrust FN, engine unit thrust FS, and engine unit fuel consumption SFC.

[0105] In order to further illustrate the technical solution and effects of the present invention, the following specific examples are provided:

[0106] Specific example: A method for calculating the performance of a pulse engine as a whole, including the following calculation steps:

[0107] (1) This specific implementation scheme takes the calculation of the design point of a 500kgf turbofan engine as an example. Before calculating the performance parameters of the whole machine, it is necessary to calculate the average parameters of the PDC outlet section;

[0108] (2) First, input the atmospheric conditions of the engine: the altitude and Mach number are both 0. Through the program calculation, the total temperature of the air in the inlet duct T1 = 288.15K and the total pressure P1 = 101325Pa;

[0109] (3) Before calculating the compression components, input fan pressure ratio PRF = 2.5, bypass ratio BPR = 2.7, fan efficiency ETAF = 0.845, compressor pressure ratio PRC = 4.0, compressor efficiency ETAC = 0.82, and air flow Wa = 9.5 kg / s. The calculation yields:

[0110] Fan outlet total temperature T 21 =391.6993K, total pressure at fan outlet P 21 =253312.5Pa, compressor outlet total temperature T3=681.8113K, compressor outlet total pressure P3=1418550.0Pa.

[0111] (4) The compressor outlet parameters are transferred to the pulse detonation combustion chamber module, and the number of detonation combustion chamber tubes NUMB = 8, tube length L = 1.2m, tube diameter D = 0.06m, operating frequency f = 40, and total temperature of the combustion chamber outlet T4 = 1500K are input. By calculation, it can be obtained:

[0112] The total pressure at the combustion chamber outlet is P4 = 1892190.3Pa, the oil-gas ratio is FAR4 = 0.02471, and the outlet gas flow rate is W f =9.734745kg / s, equivalent pressure ratio PR PDE =1.33389;

[0113] (5) Turbine module inlet parameters, (or:) known combustion chamber outlet total temperature and total pressure, high and low pressure compressor module calculated power input, high and low turbine efficiency ET HP =0.86, ET LP =0.87, through iterative calculation we can get:

[0114] The total temperature at the turbine outlet is T5 = 1482.0625K, the total pressure at the turbine outlet is P5 = 867997.3125Pa,

[0115] (6) Total pressure loss DP in the bypass DU =0.045, Mach number Ma=0.6. Determine whether the total pressure of the inner and outer ducts is similar. If not, continue to iterate the fan pressure ratio until the pressure is balanced. After mixing:

[0116] The total temperature at the mixing chamber outlet is T6 = 606.5755K, and the total pressure at the mixing chamber outlet is P6 = 242611.7500Pa;

[0117] (7) The total temperature and pressure at the nozzle inlet are known, and the velocity coefficient C V =0.985, after isentropic calculation, we know:

[0118] Nozzle outlet area A9 = 0.0248 m 2 , air flow velocity V9=443.0268m / s;

[0119] (8) In summary, the engine performance parameters can be calculated as follows:

[0120] Engine thrust FN = 494.1491 kgf;

[0121] Engine unit thrust FS = 52.0157 kgf / (kg / s);

[0122] Engine specific fuel consumption SFC = 0.5504kg / (kgf*h).

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calculating the overall performance of a pulse detonation turbofan engine, characterized in that: The following steps are involved: Step 1: using a variable specific heat calculation method, the design point performance calculations are performed on the air inlet, fan components, compressor components, mixing chamber and tail nozzle of the pulse detonation turbofan engine in turn, and the inner and outer bypass of the pulse detonation turbofan engine are determined according to the engine bypass ratio BPR and the fan pressure ratio PRF in the design point; Step 2, calculate the outlet total temperature T3 and outlet total pressure P3 of the compressor components in the inner channel, and then according to the compressor outlet total temperature T3 and outlet total pressure P3 and the detonation tube number NUMB, tube length L, tube diameter D, operating frequency f and detonation combustion chamber outlet total temperature T4 of the detonation combustion chamber, and take the total temperature and total pressure of the pressure platform area at the thrust wall of the detonation chamber as the equivalent total temperature and total pressure at the outlet of the detonation chamber, according to the detonation wave structure model, the average parameters of the pulse detonation combustion chamber outlet are obtained; Step 3: According to the total temperature T4, total pressure P4 and high-pressure turbine efficiency ET of the detonation combustion chamber outlet HP , low pressure turbine efficiency ET LP , the total temperature T5 and total pressure P5 of the turbine outlet are obtained by iterative calculation, which are the internal channel outlet parameters of the pulse detonation engine; Step 4: Based on the known total pressure loss DP in the outer duct DU , Mach number Ma, judge whether the static pressure of inner and outer culvert is balanced. If it is close, perform the design point performance calculation of mixing chamber and tail nozzle. Otherwise, continue to iterate and calculate the fan pressure ratio PRF until the static pressure of inner and outer culvert is balanced. At this time, the static pressure residual of inner and outer culvert is ≤e -4 ; Finally, the engine performance parameters are obtained, including engine thrust FN, engine unit thrust FS, and engine unit fuel consumption SFC.

2. The method for calculating the overall performance of a pulse detonation turbofan engine according to claim 1, characterized in that: The specific process of calculating the outlet total temperature T3 and outlet total pressure P3 of the compressor components in the inner channel in step 2 is: Step 21: Under the conditions of a given flight Mach number Ma and a flight altitude H of zero, according to the atmospheric temperature T of the standard atmosphere at sea level s0 With atmospheric pressure P s0 The total temperature T1 and total pressure P1 of the air in the intake duct are calculated by the calculation formula of total parameters and static parameters; Step 22: Calculate the outlet total temperature T of the fan component by using the fan / compressor pressure ratio calculation formula according to the engine bypass ratio BPR, the fan pressure ratio PRF of the fan component, the fan efficiency ETAF, the compressor pressure ratio CPR, the compressor efficiency ETAC, and the air flow Wa. 21 and outlet total pressure P 21 And the compressor outlet total temperature T3 and outlet total pressure P3.

3. The method for calculating the overall performance of a pulse detonation turbofan engine according to claim 1, characterized in that: The specific calculation process of the average parameters of the pulse detonation combustion chamber outlet in step 2 is: According to the detonation wave structure model, the calculation formula for the total pressure and total temperature at the thrust wall of the detonation chamber is: T H =T CJ [1-(γ2-1) / 2Ma CJ ] 2 , Where: P H is the pressure at the thrust wall; P CJ is the pressure at the CJ point of the detonation wave; T H is the temperature at the thrust wall; T CJ is the temperature of the detonation wave CJ point, γ is the specific heat ratio; Ma CJ Mach number of the detonation wave CJ point; The working fluid in the pulse detonation combustion chamber flows radially and uniformly, the flow rates at the inlet and outlet of the pulse detonation combustion chamber are equal in the same detonation cycle, the pressure platform, pressure decay and filling stages of the pulse detonation combustion chamber are all isentropic thermodynamic processes, the back propagation of the detonation wave of the pulse detonation combustion chamber is ignored, and under ideal conditions with only 20-25% pressure loss and no time lag between the filling stage of the pulse detonation combustion chamber and the formation of the detonation wave at the closed end, the average parameters of the outlet of the pulse detonation combustion chamber are calculated using NASA's chemical balance application software, and the average parameters of the outlet include the flow rate W of the outlet of the pulse detonation combustion chamber. g4 , outlet total temperature T4, outlet total pressure P t , the outlet oil-gas ratio FAR4, as the equivalent total parameter of the detonation combustion chamber outlet, is used to calculate the performance of the pulse detonation turbine engine.

4. The method for calculating the overall performance of a pulse detonation turbofan engine according to claim 3, characterized in that: The outlet total temperature T4, outlet total pressure P t The specific calculation process is: First, the total pressure in the pressure plateau area is: p plateau =d A1 p s,fill , Where p s，fill is the static pressure in the pulse detonation combustion chamber after filling is completed, δ A1 It is a gas characteristic parameter, which characterizes the pressure increase ratio of the total pressure in the pressure platform area relative to the static pressure in the filling stage. k1 and k2 are the specific heat ratio of the fuel-air mixture before detonation and the specific heat ratio of the products after detonation, respectively. Under isentropic conditions, according to the relationship between sound velocity and temperature, the total temperature of the pressure platform area after the detonation wave is initiating, the sound velocity c after the detonation is obtained. b Calculated by the following formula, δ A2 It is a characteristic parameter to characterize the pressure decay. c b =V CJ / d A2 , The propagation time of the blast wave is t CJ It is obtained from the following formula, L is the length of the pulse detonation combustion chamber, V fill is the filling velocity of the pulse detonation combustion chamber at the initial moment. Duration of pressure plateau area t plateau Calculated by the following formula, where δ B is the gas characteristic parameter, which characterizes its propagation time t with the detonation wave CJ Ratio of: t plateau =δ B t CJ , Duration of the pressure decay phase t decay Calculated by the following formula, where function f n (δ A2 ) According to the thrust wall pressure decay function table with time: t decay =t CJ d A2 [f n (d A2 )-1]; Finally, the calculation formula for filling time is: In summary, the total parameters and corresponding time of the filling stage, pressure platform stage and pressure decay stage are calculated by the above formulas. The calculation formula for the working time of the detonation chamber is: t cycle =t CJ +t plateau +t decay , The average total temperature and total pressure at the outlet of the pulse detonation combustion chamber can also be calculated: in: Where u(t) is the air flow velocity at time t, D tube is the pipe diameter, N tube is the number of tubes, f is the operating frequency, P tout That is equivalent to the total pressure P4 at the outlet of the detonation chamber, T tout That is equivalent to the total temperature T4 at the detonation chamber outlet.

5. The method for calculating the overall performance of a pulse detonation turbofan engine according to claim 1, characterized in that: The specific calculation process of the total pressure P5 in step 3 is: The residual equation of the whole machine performance model is established: ERR=(P 5I -P 5O ) / P 5I P5=f(FanPR), Where P 5I is the total pressure at the outlet of the low-pressure turbine, P 5O is the total pressure at the outer duct outlet, and the independent variable is the fan pressure ratio; that is, by changing the fan pressure ratio, the total pressure of the two sections is adjusted to make them basically consistent, reducing the mixing loss and ensuring the stable operation of the mixing chamber.

6. The method for calculating the overall performance of a pulse detonation turbofan engine according to claim 1, characterized in that: The design point of the mixing chamber in step 4 is obtained by the static pressure balance equation of the inner and outer ducts at the mixing chamber inlet, the total temperature T6 and the total pressure P6 of the mixing chamber outlet, the total temperature and pressure of the tail nozzle inlet, and the velocity coefficient C V After isentropic calculation, the tail nozzle outlet area A9 and air flow velocity V9 are obtained.

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